title: The role of intact oleosin for stabilization and function of oleosomes.
abstract: Lipid storage in plants is achieved among all plant species by formation of oleosomes, enclosing oil (triacylglycerides) in small subcellular droplets. Seeds are rich in this pre-emulsified oil to provide a sufficient energy reservoir for growing. The triacylglyceride core of the oleosomes is surrounded by a phospholipid monolayer containing densely packed proteins called oleosins. They are anchored in the triacylglycerides core with a hydrophobic domain, while the hydrophilic termini remain on the surface. These specialized proteins are expressed during seed development and maturation. Particularly, they play a major role in the stabilization and function of oleosomes. To better understand the importance of oleosins for oleosome stabilization, enzymatic digestion of oleosins was performed. This made it possible to compare and correlate changes in the molecular structure of oleosins and changing macroscopic properties of oleosomes. Tryptic digestion cleaves the hydrophilic part of the oleosins, which is accompanied by a loss of secondary structures as evidenced by Fourier-transform infrared and sum frequency generation spectra. After digestion, the ability of oleosins to stabilize oil-water or air-water interfaces was lost. The surface charge and the associated aggregation behavior of oleosomes are governed by interactions typical of proteins before digestion and by interactions typical of phospholipids after digestion.
authors.affiliation: Max Planck Institute for Polymer Research , Ackermannweg 10, 55128 Mainz, Germany.
authors.forename: Sania
authors.initials: S
authors.lastname: Maurer
authors.forename: Gustav
authors.initials: G
authors.lastname: Waschatko
authors.forename: Denise
authors.initials: D
authors.lastname: Schach
authors.forename: Birgitta I
authors.initials: BI
authors.lastname: Zielbauer
authors.forename: Jakob
authors.initials: J
authors.lastname: Dahl
authors.forename: Tobias
authors.initials: T
authors.lastname: Weidner
authors.forename: Mischa
authors.initials: M
authors.lastname: Bonn
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Vilgis
mesh_terms: D000388:Air; D002942:Circular Dichroism; D004655:Emulsions / Q000737:chemistry; D006368:Helianthus / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D010938:Plant Oils / Q000737:chemistry; D010940:Plant Proteins / Q000737:chemistry* / Q000378:metabolism; D013025:Glycine max / Q000378:metabolism; D017550:Spectroscopy, Fourier Transform Infrared; D014867:Water / Q000737:chemistry
chemical_list: D004655:Emulsions; D010938:Plant Oils; D010940:Plant Proteins; C079350:oleosin, Helianthus annuus; D014867:Water